If you put same ROM files to the emulator it is will working? The ROM files which are included in the latest ep128emu ROM pack are working for me.
If the EXOS EPROM are working normaly then I think the problem with the cartridge (connector/pcb/eprom). For example one address line have wrong connection, then some ROM area will changed.
Another possibility: Too slow EPROMs also can do some mystic problems. The EXOS 2.4 set no memory waits at default then possible some too slow EPROMs will work with 2.1 and not with 2.4
At the relabeled chinese EPROMs you don't know the original speed rate
Unfortunately many European seller also sell a chinese fake chips
If your programer can read the manufacturer ID and it is not match with the labeled name then easy to know it is a fake chip... also good idea see the chip size under the windows. The modern (not older than 25 years
) EPROMs have a very little chips. If the chip near to same size with the window then it is old one from early 80's, which are relabeled, and possible it is a slow one.
